Water potential Knowledge-Based Download PDF

Questions

1. 1.

   A plant cell has a solute potential ($\Psi_s$) of -0.8 MPa and a pressure potential ($\Psi_p$) of +0.3 MPa. What is the total water potential ($\Psi$) of this cell?

   • A) -0.5 MPa
   • B) -1.1 MPa
   • C) +0.5 MPa
   • D) +1.1 MPa
2. 2.

   At the point of incipient plasmolysis, the protoplast of a plant cell begins to pull away from the cell wall without exerting outward force. Which statement correctly describes the pressure potential and total water potential of the cell at this stage?

   • A) Pressure potential is at its maximum positive value, making total water potential zero.
   • B) Solute potential becomes zero, meaning total water potential equals the pressure potential.
   • C) Pressure potential is equal to zero, meaning total water potential equals the solute potential.
   • D) Pressure potential becomes negative, causing total water potential to exceed solute potential.
3. 3.

   A mature plant cell is placed in pure water at standard atmospheric pressure and allowed to reach dynamic equilibrium. Which statement accurately describes the water potential components of this cell once it is fully turgid?

   • A) The solute potential increases to zero, while the pressure potential drops to a negative value.
   • B) The pressure potential drops to zero, making total water potential solely dependent on the solute potential.
   • C) The pressure potential is equal in magnitude and opposite in sign to the solute potential, resulting in an overall water potential of zero.
   • D) The total water potential becomes more negative than the solute potential because the cell wall prevents any build-up of pressure.
4. 4.

   Which change occurs to the solute potential and the overall water potential of an aqueous solution when additional solute is dissolved in it in an open container?

   • A) Both the solute potential and the overall water potential decrease to more negative values.
   • B) The solute potential becomes more negative, while the overall water potential remains at zero.
   • C) The solute potential becomes more positive, while the overall water potential becomes more negative.
   • D) Both the solute potential and the overall water potential increase to positive values.
5. 5.

   Which statement correctly describes water potential and predicts the direction of net water movement across a selectively permeable membrane?

   • A) Net water movement occurs from a region of lower water potential to a region of higher water potential down a pressure gradient.
   • B) The addition of solutes increases the water potential of a solution, causing water to move toward areas of higher solute concentration.
   • C) Pure water has a water potential of zero at standard atmospheric pressure, and water moves toward regions with lower water potential.
   • D) Solute potential is always positive, meaning water flows toward solutions containing higher amounts of dissolved substances.